Exposure apparatus and method for producing device

ABSTRACT

An exposure apparatus includes a projection optical system for projecting a pattern on a reticle onto an object to be exposed. The apparatus also includes a reference mark that serves as a reference for an alignment between the reticle and the object. The apparatus also includes a first fluid that has a refractive index of 1 or greater, and fills a space between at least part of said projection optical system and the object and a space between at least part of said projection optical system and the reference mark. In addition, an alignment mechanism aligns the object by using said projection optical system and the first fluid.

CROSS-REFERENCE

This is a Divisional of U.S. patent application Ser. No. 11/141,518filed Jun. 1, 2005, which in turn is a Continuation of InternationalApplication No. PCT/JP03/015667 filed Dec. 8, 2003 claiming theconventional priority of Japanese patent Application No. 2002-357962filed on Dec. 10, 2002. The disclosures of these applications areincorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid immersion exposure apparatusand a liquid immersion exposure method for performing the exposure withan image of a pattern projected by a projection optical system in astate in which at least a part of a space between the projection opticalsystem and a substrate is filled with a liquid. The present inventionalso relates to a method for producing a device by using the exposureapparatus.

2. Description of the Related Art

Semiconductor devices and liquid crystal display devices are producedwith the so-called photolithography technique in which a pattern formedon a mask is transferred onto a photosensitive substrate. The exposureapparatus, which is used in the photolithography step, includes a maskstage for supporting the mask and a substrate stage for supporting thesubstrate. The pattern on the mask is transferred onto the substrate viaa projection optical system while successively moving the mask stage andthe substrate stage. In recent years, it is demanded to realize thehigher resolution of the projection optical system in order to respondto the further advance of the higher integration of the device pattern.As the exposure wavelength to be used is shorter, the resolution of theprojection optical system becomes higher. As the numerical aperture ofthe projection optical system is larger, the resolution of theprojection optical system becomes higher. Therefore, the exposurewavelength, which is used for the exposure apparatus, is shortened yearby year, and the numerical aperture of the projection optical system isincreased as well. The exposure wavelength, which is dominantly used atpresent, is 248 nm of the KrF excimer laser. However, the exposurewavelength of 193 nm of the ArF excimer laser, which is shorter than theabove, is also practically used in some situations. When the exposure isperformed, the depth of focus (DOF) is also important in the same manneras the resolution. The resolution R and the depth of focus δ arerepresented by the following expressions respectively.R=k ₁ ·λ/NA   (1)δ=±k ₂ ·λ/NA ²   (2)

In the expressions, λ represents the exposure wavelength, NA representsthe numerical aperture of the projection optical system, and k₁ and k₂represent the process coefficients. According to the expressions (1) and(2), the following fact is appreciated. That is, when the exposurewavelength λ is shortened and the numerical aperture NA is increased inorder to enhance the resolution R, then the depth of focus δ isnarrowed.

If the depth of focus δ is too narrowed, it is difficult to match thesubstrate surface with respect to the image plane of the projectionoptical system. It is feared that the margin is insufficient during theexposure operation. Accordingly, the liquid immersion method has beensuggested, which is disclosed, for example, in International PublicationNo. 99/49504 as a method for substantially shortening the exposurewavelength and widening the depth of focus. In this liquid immersionmethod, the space between the lower surface of the projection opticalsystem and the substrate surface is filled with a liquid such as wateror any organic solvent to utilize the fact that the wavelength of theexposure light beam in the liquid is 1/n as compared with that in theair (n represents the refractive index of the liquid, which is about 1.2to 1.6 in ordinary cases) so that the resolution is improved and thedepth of focus is magnified about n times.

In the exposure apparatus as described above, the detecting light beamis radiated onto the substrate surface during the exposure of thesubstrate, and the substrate surface position is detected by receivingthe reflected light beam. The positional relationship between thesubstrate surface and the image plane of the pattern formed through theprojection optical system is appropriately adjusted on the basis of theresult of the detection. However, in the case of the liquid immersionexposure apparatus based on the liquid immersion method, the liquidexists between the projection optical system and the substrate, whichbrings about the following possibility. That is, it is impossible tocorrectly detect the surface position of the substrate surface by beingaffected, for example, by the temperature change of the liquid, and thepositional relationship between the image plane of the pattern and thesubstrate surface is not adjusted appropriately. Similarly, when thealignment mark on the substrate is detected through the liquid, thefollowing possibility arises. That is, it is impossible to correctlydetect the mark on the substrate by being affected, for example, by thetemperature change of the liquid, and the positional alignment betweenthe mask and the substrate is not performed correctly.

SUMMARY OF THE INVENTION

The present invention has been made taking the circumstances asdescribed above into consideration, an object of which is to provide aliquid immersion exposure apparatus and a liquid immersion exposuremethod which make it possible to expose a substrate at a satisfactorypattern transfer accuracy when the exposure process is performed in astate in which a space between a projection optical system and thesubstrate is filled with a liquid. Another object of the presentinvention is to provide a liquid immersion exposure apparatus and aliquid immersion exposure method which make it possible to bring aboutan optimum state by adjusting the positional relationship between asubstrate surface and an image plane of a pattern. Still another objectof the present invention is to provide a liquid immersion exposureapparatus and a liquid immersion exposure method which make it possibleto correctly perform the positional alignment (alignment) for asubstrate.

In order to achieve the objects as described above, the presentinvention adopts the following constructions corresponding to FIGS. 1 to7 as illustrated in embodiments. However, parenthesized numerals orsymbols affixed to respective elements merely exemplify the elements byway of example, with which it is not intended to limit the respectiveelements.

According to a first aspect of the present invention, there is providedan exposure apparatus (EX) for exposing a substrate (P) by transferringan image of a pattern through a liquid (50) onto the substrate (P),comprising a projection optical system (PL) which projects the image ofthe pattern onto the substrate; a first substrate stage (PST) whichholds the substrate (P); a liquid supply unit (1) which supplies theliquid (50) to a side of an image plane of the projection optical system(PL); and a surface-detecting system (14) which detects surfaceinformation about a surface of the substrate (P) not through the liquid(50); wherein the substrate (P) is subjected to liquid immersionexposure while adjusting a positional relationship between the surfaceof the substrate (P) and the image plane formed through the liquid (50)by the projection optical system (PL) on the basis of the detectedsurface information.

According to the present invention, the surface information about thesubstrate surface is detected not through the liquid for the liquidimmersion exposure, and then the liquid immersion exposure is performedon the basis of the information. Therefore, it is possible to correctlyperform the adjustment of the positional relationship between thesubstrate surface and the image plane formed through the liquid, and thepositional alignment between each of the shot areas on the substrate andthe projection position of the pattern image, without being affected,for example, by the temperature change of the liquid. Further, it isunnecessary to construct any other alignment system in order to respondto the liquid immersion. The conventional detecting system can beutilized as it is.

According to a second aspect of the present invention, there is providedan exposure apparatus (EX) for exposing a plurality of shot areas (SH1to SH20) on a substrate (P) by successively exposing the plurality ofshot areas on the substrate (P) with an image of a pattern through aliquid (50); the exposure apparatus comprising a projection opticalsystem (PL) which projects the image of the pattern onto the substrate;a first substrate stage (PST) which holds the substrate (P); a liquidsupply unit (1) which supplies the liquid (50) to a side of an imageplane of the projection optical system (PL); and a first alignmentsystem (18) which detects an alignment mark on the substrate (P) notthrough the liquid (50); wherein the substrate (P) is subjected toliquid immersion exposure while performing alignment of the substrate(P) and the pattern on the basis of a result of the detection performedby the first alignment system (18).

According to the present invention, the alignment mark on the substrateis detected not through the liquid for the liquid immersion exposure,and then the liquid immersion exposure is performed on the basis of theinformation. Therefore, it is possible to correctly perform theadjustment of the positional relationship between the substrate surfaceand the image plane formed through the liquid, and the positionalalignment between each of the shot areas on the substrate and theprojection position of the pattern image, without being affected, forexample, by the temperature change of the liquid, in the same manner asin the exposure apparatus according to the first aspect. Further, it isunnecessary to construct any other alignment system in order to respondto the liquid immersion. The conventional detecting system can beutilized as it is.

According to the present invention, there is provided a method forproducing a device, characterized by using the exposure apparatus asdefined in any one of the aspects described above.

According to a third aspect of the present invention, there is provideda liquid immersion exposure method for exposing a substrate bytransferring an image of a pattern onto the substrate (P) through aliquid (50); the liquid immersion exposure method comprising a step (S2,S4) of determining a surface information about a substrate surface byperforming measurement not through the liquid supplied onto thesubstrate (P); a step (S5) of supplying the liquid onto the substrate;and a step (S8) of performing liquid immersion exposure for thesubstrate while adjusting a positional relationship between thesubstrate surface and an image plane formed through the liquid on thebasis of the determined surface information. According to this method,the surface information about the substrate surface is determined by themeasurement not through the liquid. Therefore, it is possible to executethe positioning for the substrate correctly and easily without beingeffected by any physical change such as the temperature change of theliquid.

According to a fourth aspect of the present invention, there is provideda liquid immersion exposure method for exposing a substrate (P) bytransferring an image of a pattern onto the substrate through a liquid(50), comprising a step (S1) of detecting an alignment mark on thesubstrate when the liquid is not supplied onto the substrate; a step(S5) of supplying the liquid onto the substrate; and a step (S8) ofperforming liquid immersion exposure for the substrate while performingalignment of the pattern and the substrate onto which the liquid hasbeen supplied, on the basis of a result of the detection of thealignment mark. According to this method, the alignment is performed forthe shot area on the substrate in the state not through the liquid (drycondition). Therefore, it is possible to execute the positioning for theshot area on the substrate correctly and easily without being effectedby any physical change such as the temperature change of the liquid tobe used for the liquid immersion exposure. On the other hand, theexposure operation is performed in the state in which the liquid issupplied (wet condition). Therefore, it is possible to perform theexposure with a wide depth of focus. Further, the conventional apparatuscan be used for the alignment system. Therefore, it is possible tosuppress the increase in the equipment cost which would be otherwiseincreased when the-liquid immersion exposure is performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic arrangement illustrating an embodiment of theexposure apparatus of the present invention.

FIG. 2 shows a positional relationship among a tip of a projectionoptical system, a liquid supply unit, and a liquid recovery unit.

FIG. 3 shows an exemplary arrangement of supply nozzles and recoverynozzles.

FIG. 4 shows a plan view illustrating a substrate stage for holding asubstrate.

FIG. 5 shows a schematic arrangement illustrating another embodiment ofthe exposure apparatus of the present invention.

FIG. 6 shows a schematic arrangement illustrating still anotherembodiment of the exposure apparatus of the present invention.

FIG. 7 shows a flow chart illustrating exemplary steps for producing asemiconductor device.

FIG. 8 shows a flow chart illustrating a procedure for exposing asubstrate with a mask pattern by using the exposure apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

An explanation will be made below about the exposure apparatus and themethod for producing the device according to the present invention. FIG.1 shows a schematic arrangement illustrating an embodiment of theexposure apparatus of the present invention.

With reference to FIG. 1, an exposure apparatus EX includes a mask stageMST which supports a mask M, a substrate stage PST which supports asubstrate P, an illumination optical system IL which illuminates, withan exposure light beam EL, the mask M supported by the mask stage MST, aprojection optical system PL which performs projection exposure for thesubstrate P supported by the substrate stage PST with an image of apattern of the mask M illuminated with the exposure light beam EL, and acontrol unit CONT which collectively controls the overall operation ofthe exposure apparatus EX.

The embodiment of the present invention will now be explained asexemplified by a case of the use of the scanning type exposure apparatus(so-called scanning stepper) as the exposure apparatus EX in which thesubstrate P is exposed with the pattern formed on the mask M whilesynchronously moving the mask M and the substrate P in mutuallydifferent directions (opposite directions) in the scanning directions.In the following explanation, the Z axis direction resides in thedirection which is coincident with the optical axis AX of the projectionoptical system PL, the X axis direction resides in the synchronousmovement direction (scanning direction) for the mask M and the substrateP in the plane perpendicular to the Z axis direction, and Y axisdirection resides in the direction (non-scanning direction)perpendicular to the Z axis direction and the Y axis direction. Thedirections about the X axis, the Y axis, and the X axis are designatedas θX, θY, and θZ directions respectively. The term “substrate” referredto herein includes those obtained by applying a resist on asemiconductor wafer, and the term “mask” includes a reticle formed witha device pattern to be subjected to the reduction projection onto thesubstrate.

The illumination optical system IL is used so that the mask M, which issupported on the mask stage MST, is illuminated with the exposure lightbeam EL. The illumination optical system IL includes, for example, anexposure light source, an optical integrator which uniformizes theilluminance of the light flux radiated from the exposure light source, acondenser lens which collects the exposure light beam EL supplied fromthe optical integrator, a relay lens system, and a variable fielddiaphragm which sets the illumination area on the mask M illuminatedwith the exposure light beam EL to be slit-shaped. The predeterminedillumination area on the mask M is illuminated with the exposure lightbeam EL having a uniform illuminance distribution by the illuminationoptical system IL. Those usable as the exposure light beam EL radiatedfrom the illumination optical system IL include, for example, emissionlines (g-ray, h-ray, i-ray) in the ultraviolet region radiated, forexample, from a mercury lamp, far ultraviolet light beams (DUV lightbeams) such as the KrF excimer laser beam (wavelength: 248 nm), andvacuum ultraviolet light beams (VUV light beams) such as the ArF excimerlaser beam (wavelength: 193 nm) and the F₂ laser beam (wavelength: 157nm). In this embodiment, the ArF excimer laser beam is used.

The mask stage MST supports the mask M. The mask stage MST istwo-dimensionally movable in the plane perpendicular to the optical axisAX of the projection optical system PL, i.e., in the XY plane, and it isfinely rotatable in the θZ direction. The mask stage MST is driven by amask stage-driving unit MSTD such as a linear motor. The maskstage-driving unit MSTD is controlled by the control unit CONT. Amovement mirror 58 is provided on the mask stage MST. A laserinterferometer 57 is provided at a position opposed to the movementmirror 58. The position in the two-dimensional direction and the angleof rotation of the mask M on the mask stage MST are measured inreal-time by the laser interferometer 57. The result of the measurementis outputted to the control unit CONT. The control unit CONT drives themask stage-driving unit MSTD on the basis of the result of themeasurement obtained by the laser interferometer 57 to thereby positionthe mask M supported on the mask stage MST.

The projection optical system PL projects the pattern on the mask M ontothe substrate P at a predetermined projection magnification β to performthe exposure. The projection optical system PL includes a plurality ofoptical elements (lenses). The optical elements are supported by abarrel PK as a metal member. In this embodiment, the projection opticalsystem PL is based on the reduction system having the projectionmagnification β which is, for example, ¼ or ⅕. The projection opticalsystem PL may be any one of the 1× magnification system and themagnifying system. The optical element (lens) 60 is exposed from thebarrel PK on the side of the tip (on the side of the substrate P) of theprojection optical system PL of this embodiment. The optical element 60is provided detachably (exchangeably) with respect to the barrel PK.

The substrate stage (first substrate stage) PST supports the substrateP. The substrate stage PST comprises a Z stage 51 which holds thesubstrate P by the aid of a substrate holder, an XY stage 52 whichsupports the Z stage 51, and a base 53 which supports the XY stage 52.The substrate stage PST is driven by a substrate stage-driving unit PSTDsuch as a linear motor. The substrate stage-driving unit PSTD iscontrolled by the control unit CONT.

The surface information about the surface of the substrate P(inclination information and position information in the Z axisdirection) is detected by a focus/leveling-detecting system 14 as asurface-detecting system. The focus/leveling-detecting system 14includes a light-emitting system 14A which emits a detecting light beamonto the surface of the substrate P, and a light-receiving system 14Bwhich receives a reflected light beam from the substrate P. The resultof detection of the focus/leveling-detecting system 14 is outputted tothe control unit CONT. The control unit CONT drives the Z stage 51 onthe basis of the result of the detection of the focus/leveling-detectingsystem 14 to adjust the position (focus position) in the Z axisdirection and the angle of inclination of the substrate P held on the Zstage 51. Accordingly, the surface of the substrate P is adjusted tomatch the optimum state with respect to the image plane of theprojection optical system PL in the auto-focus manner and theauto-leveling manner. The Z stage and the XY stage may be formed as anintegrated body.

A movement mirror 54, which is movable together with the substrate stagePST with respect to the projection optical system PL, is provided on thesubstrate stage PST (Z stage 51). A laser interferometer 55 is providedat a position opposed to the movement mirror 54. The angle of rotationand the position in the two-dimensional direction of the substrate P onthe substrate stage PST are measured in real-time by the laserinterferometer 55. The result of the measurement is outputted to thecontrol unit CONT. The control unit CONT drives the XY stage 52 by theaid of the substrate stage-driving unit PSTD on the basis of the resultof the measurement of the laser interferometer 55 to thereby adjust theposition of the substrate P in the XY directions (position in thedirections substantially parallel to the image plane of the projectionoptical system PL). Thus, the substrate P, which is supported on thesubstrate stage PST, is positioned.

A substrate alignment system (first alignment system) 18, which detectsan alignment mark on the substrate P or a fiducial mark provided on theZ stage 51 (as described later on), is arranged in the vicinity of thetip of the projection optical system PL. A mask alignment system (secondalignment system) 19, which detects a fiducial mark on the Z stage 51through the mask M and the projection optical system PL, is provided inthe vicinity of the mask stage MST.

An arrangement of the autofocus/leveling detecting system 14 isdisclosed, for example, in Japanese Patent Application Laid-open No.8-37149 (corresponding to U.S. Pat. No. 6,195,154). An arrangement ofthe substrate alignment system 18 is disclosed in Japanese PatentApplication Laid-open No. 4-65603 (corresponding to U.S. Pat. No.5,493,403). Further, an arrangement of the mask alignment system 19 isdisclosed in Japanese Patent Application Laid-open No. 7-176468(corresponding to U.S. Pat. No. 5,646,413). The disclosures of thesedocuments are incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

In this embodiment, the liquid immersion method is applied in order thatthe resolution is improved by substantially shortening the exposurewavelength and the depth of focus is substantially widened. Therefore,the space between the surface of the substrate P and the tip surface(lower surface) 7 of the optical element (lens) 60 of the projectionoptical system PL on the side of the substrate P is filled with thepredetermined liquid 50 at least during the period in which the image ofthe pattern on the mask M is transferred onto the substrate P. Asdescribed above, the lens 60 is exposed on the tip side of theprojection optical system PL, and the liquid 50 is supplied to makecontact with only the lens 60. Accordingly, the barrel PK composed ofthe metal is prevented from any corrosion or the like. In thisembodiment, pure water is used for the liquid 50. The exposure lightbeam EL, which is not limited to only the ArF excimer laser beam, can betransmitted through pure water, even when the exposure light beam EL is,for example, the emission line (g-ray, h-ray, i-ray) in the ultravioletregion radiated, for example, from a mercury lamp or the far ultravioletlight beam (DUV light beam) such as the KrF excimer laser beam(wavelength: 248 nm).

The exposure apparatus EX includes a liquid supply unit 1 which suppliesthe predetermined liquid 50 to the space 56 between the substrate P andthe tip surface (end surface of the lens 60) 7 of the projection opticalsystem PL, i.e., to the side of the image plane of the projectionoptical system PL, and a liquid recovery unit 2 which recovers theliquid 50 from the space 56. The liquid supply unit 1 is provided tofill at least a part of the space between the projection optical systemPL and the substrate P with the liquid 50. The liquid supply unit 1includes, for example, a tank for accommodating the liquid 50, and apressurizing pump. One end of a supply tube 3 is connected to the liquidsupply unit 1. Supply nozzles 4 are connected to the other end of thesupply tube 3. The liquid supply unit 1 supplies the liquid 50 to thespace 56 through the supply tube 3 and the supply nozzles 4.

The liquid recovery unit 2 includes, for example, a suction pump, and atank for accommodating the recovered liquid 50. One end of a recoverytube 6 is connected to the liquid recovery unit 2. Recovery nozzles 5are connected to the other end of the recovery tube 6. The liquidrecovery unit 2 recovers the liquid 50 from the space 56 through therecovery nozzles 5 and the recovery tube 6. When the space 56 is filledwith the liquid 50, then the control unit CONT drives the liquid supplyunit 1 so that the liquid 50, which is in a predetermined amount perunit time, is supplied to the space 56 through the supply tube 3 and thesupply nozzles 4, and the control unit CONT drives the liquid recoveryunit 2 so that the liquid 50, which is in a predetermined amount perunit time, is recovered from the space 56 via the recovery nozzles 5 andthe recovery tube 6. Accordingly, the liquid 50 is retained in the space56 between the substrate P and the tip surface 7 of the projectionoptical system PL. The temperature of the liquid 50 is set, for example,to be approximately the same as the temperature in the chamber in whichthe exposure apparatus EX is accommodated.

FIG. 2 shows a partial magnified view of FIG. 1 illustrating, forexample, the lower portion of the projection optical system PL of theexposure apparatus EX, the liquid supply unit 1, and the liquid recoveryunit 2. In FIG. 2, the lens 60, which is disposed at the lowest end ofthe projection optical system PL, is formed to have a rectangular shapewhich is long in the Y axis direction (non-scanning direction) exceptfor the portion required for the end portion 60A in the scanningdirection. During the scanning exposure, a pattern image of a part ofthe mask M is projected onto the rectangular projection area disposedjust under the end portion 60A. The mask M is moved at the velocity V inthe −X direction (or in the +X direction) with respect to the projectionoptical system PL, in synchronization with which the substrate P ismoved at the velocity β·V (β is the projection magnification) in the +Xdirection (or in the −X direction) by the aid of the XY stage 52. Afterthe completion of the exposure for one shot area, the next shot area ismoved to the scanning start position in accordance with the stepping ofthe substrate P. The exposure process is successively performedthereafter for each of the shot areas in accordance in the step-and-scanmanner. This embodiment is designed so that the liquid 50 flows in themovement direction of the substrate P.

FIG. 3 shows the positional relationship among the end portion 60A ofthe projection optical system PL, the supply nozzles 4 (4A to 4C) forsupplying the liquid 50 in the X axis direction, and the recoverynozzles 5 (5A, 5B) for recovering the liquid 50. In FIG. 3, the endportion 60A of the lens 60 has a rectangular shape which is long in theY axis direction. The three supply nozzles 4A to 4C are arranged on theside in the +X direction, and the two recovery nozzles 5A, 5B arearranged on the side in the −X direction so that the end portion 60A ofthe lens 60 of the projection optical system PL is interposed thereby.The supply nozzles 4A to 4C are connected to the liquid supply unit 1through the supply tube 3, and the recovery nozzles 5A, 5B are connectedto the liquid recovery unit 2 through the recovery tube 4. Further, thesupply nozzles 8A to 8C and the recovery nozzles 9A, 9B are arranged atpositions obtained by rotating, by substantially 180°, the positions ofthe supply nozzles 4A to 4C and the recovery nozzles 5A, 5B about thecenter of the end portion 60A. The supply nozzles 4A to 4C and therecovery nozzles 9A, 9B are alternately arranged in the Y axisdirection. The supply nozzles 8A to 8C and the recovery nozzles 5A, 5Bare alternately arranged in the Y axis direction. The supply nozzles 8Ato 8C are connected to the liquid supply unit 1 through the supply tube10. The recovery nozzles 9A, 9B are connected to the liquid recoveryunit 2 through the recovery tube 11.

When the scanning exposure is performed by moving the substrate P in thescanning direction (−X direction) indicated by the arrow Xa, the liquid50 is supplied and recovered with the liquid supply unit 1 and theliquid recovery unit 2 by using the supply tube 3, the supply nozzles 4Ato 4C, the recovery tube 4, and the recovery nozzles 5A, 5B. That is,when the substrate P is moved in the −X direction, then the liquid 50 issupplied to the space between the projection optical system PL and thesubstrate P from the liquid supply unit 1 by the aid of the supply tube3 and the supply nozzles 4 (4A to 4C), and the liquid 50 is recovered tothe liquid recovery unit 2 by the aid of the recovery nozzles 5 (5A, 5B)and the recovery tube 6. The liquid 50 flows in the −X direction so thatthe space between the lens 60 and the substrate P is filled therewith.On the other hand, when the scanning exposure is performed by moving thesubstrate P in the scanning direction (+X direction) indicated by thearrow Xb, then the liquid 50 is supplied and recovered with the liquidsupply unit 1 and the liquid recovery unit 2 by using the supply tube10, the supply nozzles 8A to 8C, the recovery tube 11, and the recoverynozzles 9A, 9B. That is, when the substrate P is moved in the +Xdirection, then the liquid 50 is supplied from the liquid supply unit 1to the space between the projection optical system PL and the substrateP by the aid of the supply tube 10 and the supply nozzles 8 (8A to 8C),and the liquid 50 is recovered to the liquid recovery unit 2 by the aidof the recovery nozzles 9 (9A, 9B) and the recovery tube 11. The liquid50 flows in the +X direction so that the space between the lens 60 andthe substrate P is filled therewith. As described above, the controlunit CONT makes the liquid 50 to flow in the same direction as themovement direction of the substrate P in accordance with the movementdirection of the substrate P by using the liquid supply unit 1 and theliquid recovery unit 2. In this arrangement, for example, the liquid 50,which is supplied from the liquid supply unit 1 via the supply nozzles4, flows so that the liquid 50 is attracted and introduced into thespace 56 in accordance with the movement of the substrate P in the −Xdirection. Therefore, even when the supply energy of the liquid supplyunit 1 is small, the liquid 50 can be supplied to the space 56 withease. When the direction, in which the liquid 50 is made to flow, isswitched depending on the scanning direction, then it is possible tofill the space between the substrate P and the tip surface 7 of the lens60 with the liquid 50, and it is possible to obtain the high resolutionand the wide depth of focus, even when the substrate P is subjected tothe scanning in any one of the +X direction and the −X direction.

There is no special limitation to the shape of the nozzle describedabove. For example, two pairs of nozzles may be used for the long sideof the end portion 60A to supply and recover the liquid 50. In thisarrangement, the supply nozzles and the recovery nozzles may be arrangedand aligned vertically in order that the liquid 50 can be supplied andrecovered in any one of the +X direction and the −X direction. Althoughnot shown, the nozzles, which are used to supply and recover the liquid50, are provided at predetermined intervals around the lens 60 of theprojection optical system PL. Even when the substrate P is moved in anydirection other than the scanning direction (+X direction, −Xdirection), it is possible to made the liquid 50 to flow in the samedirection as the movement direction of the substrate P in parallel tothe movement direction of the substrate P.

FIG. 4 shows a schematic plan view illustrating the Z stage 51 as viewedfrom an upper position. The movement mirror 54 is arranged on themutually perpendicular two side surfaces of the rectangular Z stage 51.The substrate P is held by the aid of an unillustrated holder at asubstantially central portion of the Z stage 51. A plurality of shotareas SH1 to SH20 are set on the substrate P. An auxiliary plate 41,which has a flat surface having approximately the same height as that of(flush with) the surface of the substrate P, is provided around thesubstrate P. There is a gap of about 1 to 2 mm between the edge of thesubstrate P and the auxiliary plate 41. However, the liquid 50 scarcelyflows into the gap owing to the surface tension of the liquid 50. It ispossible to retain the liquid 50 under the projection optical system PLeven when the exposure is performed for those disposed in the vicinityof the circumferential edge of the substrate P.

A fiducial plate (reference member) 42 is provided integrally with theauxiliary plate 41 at one corner of the Z stage 51. The fiducial plate42 is provided with a fiducial mark PFM to be detected by the substratealignment system 18, and a fiducial mark MFM to be detected by the maskalignment system 19, while the fiducial mark PFM and the fiducial markMFM are provided in a predetermined positional relationship. The surfaceof the fiducial plate 42 is substantially flat, which also functions asa fiducial surface or reference plane for the focus/leveling-detectingsystem 14. The fiducial surface for the focus/leveling-detecting system14 may be provided on the Z stage 51 separately from the fiducial plate42. The fiducial plate 42 may be provided while being separated from theauxiliary plate 41 by about 1 to 2 mm. The fiducial mark PFM and thefiducial mark MFM may be provided on different members respectively.Further, the surface of the fiducial plate 42 is set to haveapproximately the same height as that of the surface of the substrate Pand the surface of the auxiliary plate 41. The liquid immersion portion,which is disposed under the projection optical system PL, can be movedbetween the fiducial plate 42 and the substrate P while retaining theliquid 50 under the projection optical system PL.

Next, an explanation will be made with reference to a flow chart shownin FIG. 8 about a procedure for exposing the substrate P with thepattern of the mask M by using the exposure apparatus EX describedabove.

Detection of Alignment Mark (XY Directions) under Dry Condition

The measurement process is firstly performed in a state in which theliquid is absent on the substrate P before supplying the liquid 50 fromthe liquid supply unit 1. The control unit CONT moves the XY stage 52while monitoring the output of the laser interferometer 55 so that theoptical axis AX of the projection optical system PL follows the brokenline arrow 43 shown in FIG. 4 over the shot areas SH1 to SH20. Duringthis movement, the substrate alignment system 18 detects the pluralityof alignment marks (not sown) formed on the substrate P not through theliquid (S1). The XY stage 52 is stopped when the substrate alignmentsystem 18 detects the alignment mark. As a result, the positioninformation about the respective alignment marks in the coordinatesystem defined by the laser interferometer 55 is measured. As for thedetection of the alignment marks by the substrate alignment system 18,all of the alignment marks on the substrate P may be detected, or only apart of the alignment marks may be detected. When the substratealignment system 18 can detect the alignment mark on the substrate Pwhile moving over the substrate P, it is also allowable that the XYstage 52 is not stopped.

Detection of Substrate Surface Position (Z Direction) Under DryCondition

During the movement of the XY stage 52, the surface information aboutthe substrate P is detected by the focus/leveling-detecting system 14not through the liquid (S2). The surface information is detected by thefocus/leveling-detecting system 14 for all of the shot areas SH1 to SH20on the substrate P one by one. The result of the detection is stored inthe control unit CONT while corresponding to the position of thesubstrate P in the scanning direction (X axis direction). The detectionof the surface information by the focus/leveling-detecting system 14 maybe performed for only a part of the shot areas.

The way of the movement of the XY stage 52 is not limited to the locusshown in FIG. 4. The movement may be effected so that the desireddetecting operation can be performed while making the distance as shortas possible. Alternatively, one of the detection of the positioninformation about the plurality of alignment marks and the detection ofthe surface information about the substrate P may be completed ahead ofthe other, and then the other detection may be executed thereafter.

Detection of Fiducial Mark PFM (XY Directions) under Dry Condition

When the detection of the alignment marks on the substrate P and thedetection of the surface information about the substrate P arecompleted, the control unit CONT moves the XY stage 52 so that thedetection area of the substrate alignment system 18 is positioned on thefiducial plate 42. The substrate alignment system 18 detects thefiducial mark PFM on the fiducial plate 42 to measure the positioninformation about the fiducial mark PFM in the coordinate system definedby the laser interferometer 55 (S3).

When the process for detecting the fiducial mark PFM is completed, thepositional relationship between the fiducial mark PFM and the pluralityof alignment marks on the substrate P is determined. The positionalrelationship between the plurality of alignment marks and the shot areasSH1 to SH20 is already known. Therefore, when the positionalrelationship between the fiducial mark PFM and the plurality ofalignment marks on the substrate P is determined, the positionalrelationships between the fiducial mark PFM and the plurality of shotareas SH1 to SH20 on the substrate P are consequently determinedrespectively. The predetermined positional relationship holds betweenthe fiducial mark PFM and the fiducial mark MFM. Therefore, thepositional relationships between the fiducial mark MFM and the pluralityof shot areas SH1 to SH20 on the substrate in the XY plane areconsequently determined respectively.

Detection of Surface Position of Fiducial Plate (Z Direction) under DryCondition

The control unit CONT detects the surface information about the surfaceof the fiducial plate 42 (fiducial surface) by using thefocus/leveling-detecting system 14 (S4) before or after the detection ofthe fiducial mark PFM by the substrate alignment system 18. When theprocess for detecting the surface of the fiducial plate 42 is completed,the positional relationship between the fiducial plate 42 and thesurface of the substrate P is consequently determined.

Detection of Fiducial Mark MFM (XY Directions) under Wet Condition

Subsequently, the control unit CONT moves the XY stage 52 so that thefiducial mark MFM on the fiducial plate 42 can be detected by the maskalignment system 19. Of course, the end portion 60A of the projectionoptical system PL is opposed to the fiducial plate 42 in this state. Inthis situation, the control unit CONT starts the supply and the recoveryof the liquid 50 with the liquid supply unit 1 and the liquid recoveryunit 2 to fill the space between the projection optical system PL andthe fiducial plate 42 with the liquid 50 (S5).

Subsequently, the control unit CONT performs the detection of thefiducial mark MFM through the mask M, the projection optical system PL,and the liquid 50 by using the mask alignment system 19 (S6). That is,the positional relationship between the mark on the mask M and thefiducial mark MFM is detected through the projection optical system PLand the liquid. Accordingly, the position of the mask M in the XY plane,i.e., the information about the projection position of the image of thepattern on the mask M is consequently detected through the projectionoptical system PL and the liquid 50 by using the fiducial mark MFM.

Detection of Fiducial Plate (Z Direction) under Wet Condition

The control unit CONT detects the surface of the fiducial plate 42(fiducial surface) by using the focus/leveling-detecting system 14 in astate in which the liquid 50 is supplied to the space between theprojection optical system PL and the fiducial plate 42 to measure therelationship between the surface of the fiducial plate 42 and the imageplane formed through the projection optical system PL and the liquid 50(S7). The focus/leveling-detecting system 14 is constructed so that thepositional relationship (deviation) between the detection objectivesurface and the image plane formed through the liquid 50 by theprojection optical system PL under the wet condition can be detected.The relationship between the surface of the substrate P and the imageplane formed through the projection optical system PL and the liquid 50is consequently detected by using the fiducial plate 42 by detecting thesurface of the fiducial plate 42 under the wet condition.

Alignment and Exposure under Wet Condition

When the measurement process as described above is completed, thecontrol unit CONT moves the XY stage 52 to move the liquid immersionportion disposed under the projection optical system PL onto thesubstrate P while performing the supply and the recovery of the liquid50 in order to expose each of the shot areas SH1 to SH20 on thesubstrate P. The surfaces of the fiducial plate 42, the auxiliary plate41, and the substrate P have approximately the same height respectively.Therefore, the XY stage 52 can be moved in a state in which the liquid50 is retained under the projection optical system PL.

The respective shot areas SH1 to SH20 on the substrate P are subjectedthe scanning exposure by using the respective pieces of informationdetermined during the measurement process as described above (S8). Thatis, during the scanning exposure for each of the shot areas, each of theshot areas SH1 to SH20 on the substrate P and the mask M are subjectedto the positional alignment on the basis of the information about thepositional relationship between the fiducial mark PFM and each of theshot areas SH1 to SH20 determined before the supply of the liquid 50,and the projection position information about the image of the patternon the mask M determined by using the fiducial mark MFM after the supplyof the liquid 50 (S8).

During the scanning exposure for each of the shot areas SH1 to SH20, thepositional relationship between the surface of the substrate P and theimage plane formed through the liquid 50 is adjusted without using thefocus/leveling-detecting system 14, on the basis of the informationabout the relationship between the surface of the fiducial plate 42 andthe surface of the substrate P determined before the supply of theliquid 50, and the information about the positional relationship betweenthe surface of the fiducial plate 42 and the image plane formed throughthe liquid 50 determined after the supply of the liquid 50. As describedabove, the detection with the focus/leveling-detecting system 14performed through the liquid 50 is carried out only when the surface ofthe fiducial plate 42 is detected before the start of the exposure forthe substrate P. Therefore, it is possible to perform the detectingoperation of the focus/leveling-detecting system 14 by suppressing theinfluence of the temperature change of the liquid 50 or the like to beminimum.

The surface information about the surface of the substrate P may bedetected by using the focus/leveling-detecting system 14 during thescanning exposure, which may be used to confirm the result of theadjustment of the positional relationship between the surface of thesubstrate P and the image plane. Alternatively, the surface informationabout the surface of the substrate P may be detected by using thefocus/leveling-detecting system 14 during the scanning exposure, towhich the surface information detected during the scanning exposure maybe further added to adjust the positional relationship between thesurface of the substrate P and the image plane.

In the embodiment described above, the focus/leveling-detecting system14, which radiates the detecting light beam onto the inside or in thevicinity of the projection area to form the image of the pattern of themask M therein, is used when the surface information about the substrateP is detected in the absence of liquid. However, it is also allowable touse another focus/leveling-detecting system (not shown) which is carriedon the substrate alignment system 18. The focus/leveling-detectingsystem, which is carried on the substrate alignment system 18, is usedto adjust the position of the surface of the substrate P when thealignment mark on the substrate P is detected by using the substratealignment system 18. A specified arrangement of such afocus/leveling-detecting system is disclosed, for example, in JapanesePatent Application Laid-open No. 2001-257157 (corresponding to UnitedStates Patent Publication No. 2001/0023918A), the disclosure of which isincorporated herein by reference within a range of permission of thedomestic laws and ordinances of the state designated or selected in thisinternational application.

In the embodiment described above, the positional relationship betweenthe surface of the substrate P and the image plane is adjusted by movingthe Z stage 51 which holds the substrate P. However, the mask M and/or apart of the plurality of lenses for constructing the projection opticalsystem PL may be moved to adjust the image plane to the surface of thesubstrate P. Alternatively, the wavelength of the exposure light beam ELmay be finely adjusted.

In the embodiment described above, the supply of the liquid 50 from theliquid supply unit 1 is started after the detection of the fiducial markPFM and the alignment mark on the substrate P. However, if possible, theliquid 50 may be supplied from the liquid supply unit 1 before thedetection to detect the fiducial mark PFM and the alignment mark on thesubstrate P not through the liquid while locally retaining the liquid 50on the side of the image plane of the projection optical system PL.

In the embodiment described above, the fiducial plate 42 is used tocorrelate the surface information about the substrate P measured underthe dry condition with respect to the image plane formed through theprojection optical system PL and the liquid 50. However, a predeterminedarea on the substrate P may be used as the fiducial surface in place ofthe fiducial plate 42, and the predetermined are is detected by usingthe focus/leveling-detecting system 14 under the dry condition and thewet condition to correlate the surface information about the substrate Pmeasured under the dry condition with respect to the image plane formedthrough the projection optical system PL and the liquid 50.

In the embodiment described above, the focus/leveling-detecting system14 is used for both of the dry condition and the wet condition. However,a focus/leveling-detecting system for the dry condition and afocus/leveling-detecting system for the wet condition may be providedseparately.

When the relationship (offset) between the surface information about thesubstrate P detected under the dry condition by thefocus/leveling-detecting system 14 and the image plane formed by theprojection optical system PL through the liquid is previously known,then the detection under the wet condition by thefocus/leveling-detecting system 14 may be omitted, and each of the shotareas on the substrate P may be subjected to the liquid immersionexposure while adjusting the positional relationship between the surfaceof the substrate P and the image plane formed by the projection opticalsystem PL through the liquid on the basis of the surface informationabout the substrate P measured under the dry condition. In thisprocedure, it is also allowable that the fiducial plate 42 to serve asthe fiducial surface is not provided on the substrate stage PST(provided that the fiducial mark is required).

As described above, the detection of the alignment mark on the substrateP and the detection of the surface information about the substrate P areperformed not through the liquid 50 for the liquid immersion exposure,and then the liquid immersion exposure is performed on the basis of theobtained information. Therefore, it is possible to correctly perform thepositional alignment between the mask M and each of the shot areas SH1to SH20 on the substrate P and the adjustment of the positionalrelationship between the surface of the substrate P and the image planeformed through the liquid 50.

FIG. 5 shows a modified embodiment of the present invention, whichillustrates a schematic arrangement in the vicinity of the lens 60 ofthe projection optical system PL. In FIG. 5, for the purpose ofsimplification, for example, the liquid supply unit 1, the liquidrecovery unit 2, and the substrate alignment system 18 are omitted.

An exposure apparatus EX shown in FIG. 5 includesfocus/leveling-detecting systems 61, 62 each of which has the samearrangement as that of the focus/leveling-detecting system 14 fordetecting the surface information about the surface of the substrate Pand which are provided on the both sides of the lens 60 of theprojection optical system PL with respect to the X axis. The respectivedetection areas of the focus/leveling-detecting systems 61, 62 are setat positions separated from the liquid immersion portion even when theliquid is supplied under the projection optical system PL (the liquid 50is locally retained on the side of the image plane of the projectionoptical system PL). The focus/leveling-detecting system 61 is used whenthe scanning exposure is performed while moving the substrate P in the−X direction, and the focus/leveling-detecting system 62 is used whenthe scanning exposure is performed while moving the substrate P in the+X direction.

In the case of the exposure apparatus of this embodiment, the positionalalignment (alignment) for the mask M and each of the shot areas on thesubstrate P is performed in the same manner as in the embodimentdescribed above.

In the measurement process in this embodiment, the surface position ofthe fiducial plate 42 is detected by using the focus/leveling-detectingsystem 14 in a state in which the liquid 50 is supplied to the spacebetween the projection optical system PL and the fiducial plate 42, andthe Z stage 51 is moved on the basis of the detection result so that thesurface of the fiducial plate 42 is adjusted to match the image planeformed through the projection optical system PL and the liquid 50. Inthis situation, the respective detection areas of thefocus/leveling-detecting systems 61, 62 are also positioned on thefiducial plate 42 (in this situation, the liquid is absent in thedetection areas of the focus/leveling-detecting systems 61, 62). Thesurface of the fiducial plate 42 is detected by thefocus/leveling-detecting systems 61, 62 respectively, and thus thecontrol unit CONT can determine the relationship between the image planeformed through the projection optical system PL and the liquid 50 andthe respective pieces of information detected by thefocus/leveling-detecting systems 61, 62 not through the liquid.

When the measurement process is completed as described above, thecontrol unit CONT moves the XY stage 52 while supplying and recoveringthe liquid 50 in order to expose each of the shot areas SH1 to SH20 onthe substrate P so that the liquid immersion portion, which is disposedunder the projection optical system PL, is moved onto the substrate P.The control unit CONT performs the scanning exposure for each of theshot areas SH1 to SH20 on the substrate P by using the respective piecesof information determined during the measurement process. During thescanning exposure for each of the shot areas on the substrate P, thepositional relationship between the surface of the substrate P and theimage plane formed through the projection optical system PL and theliquid 50 is adjusted by using the focus/leveling-detecting systems 61,62 which have the detection areas disposed outside the liquid immersionportion between the projection optical system PL and the substrate P,without using the focus/leveling-detecting system 14. For example, whena certain shot area on the substrate P is subjected to the scanningexposure while moving the substrate P in the −X direction, the surfaceposition information about the surface of the shot area is successivelydetected by the focus/leveling-detecting system 61 before the shot areaas the exposure objective enters the liquid immersion portion betweenthe projection optical system PL and the substrate P. Further, when theshot area passes through the liquid immersion portion between theprojection optical system PL and the substrate P, the positionalrelationship between the shot area surface and the image plane isadjusted on the basis of the surface position information detected bythe focus/leveling-detecting system 61. The relationship between theoptimum image plane and the surface information detected by thefocus/leveling-detecting system 61 is previously determined by using thefiducial plate 42. Therefore, the shot area surface can be correctlyadjusted to match the optimum image plane without being affected, forexample, by the temperature change of the liquid 50, even using only thesurface position information detected by the focus/leveling-detectingsystem 61. It goes without saying that the focus/leveling-detectingsystem 14 is appropriately used in combination during the exposure, ifnecessary, as described in the previous embodiment.

In recent years, a twin-stage type exposure apparatus appears, whichcarries two stages for holding the substrates P. The present inventionis also applicable to the twin-stage type exposure apparatus.

FIG. 6 shows a schematic arrangement of the twin-stage type exposureapparatus. The twin-stage type exposure apparatus is provided with firstand second substrate stages PST1, PST2 which are movable independentlyon a common base 71 respectively. The first and second substrate stagesPST1, PST2 includes fiducial plates 74, 75 which are constructedequivalently to the fiducial plate 42 shown in FIG. 4 respectively. Thetwin-stage type exposure apparatus has an exposure station and ameasurement/exchange station. All of the system shown in FIG. 4(including the focus/leveling-detecting system 14) except for thesubstrate alignment system 18 is carried on the exposure station. Themeasurement/exchange station is provided with a substrate alignmentsystem 72, and a focus/leveling-detecting system 73 including alight-emitting system 73A and a light-receiving system 73B.

The basic operation of the twin-stage type exposure apparatus asdescribed above is as follows. For example, the exchange and themeasurement process are performed for the substrate P on the firstsubstrate stage PST1 on the measurement/exchange station, during theexposure process for the substrate P on the second substrate stage PST2on the exposure station. When the respective operations are completed,the second substrate stage PST2 is moved to the measurement/exchangestation, concurrently with which the first substrate stage PST1 is movedto the exposure station. In this situation, the measurement and theexchange process are performed on the second substrate stage PST2, andthe exposure process is performed for the substrate P on the firstsubstrate stage PST1.

When the present invention is applied to the twin-stage type exposureapparatus, the measurement process, which is performed not through theliquid as explained in the foregoing embodiment, is performed on themeasurement/exchange station. For example, the liquid immersion exposureprocess is performed on the exposure station for the substrate P on thesecond substrate stage PST2, during which the measurement process isperformed on the measurement station for the substrate P on the firstsubstrate stage PST1 not through the liquid by using the substratealignment system 72, the focus/leveling-detecting system 73, and thefiducial plate 74. When the measurement process, which is performed notthrough the liquid, is completed, the exchange operation is performedfor the first substrate stage PST1 and the second substrate stage PST2.As shown in FIG. 6, the first substrate stage PST1 is positioned so thatthe fiducial plate 74 of the first substrate stage PST1 is opposed tothe projection optical system PL. In this state, the control unit CONTstarts the supply of the liquid 50 to fill the space between theprojection optical system PL and the fiducial plate 74 with the liquid50. The measurement process and the exposure process are performedthrough the liquid in the same manner as in the embodiment describedabove. The alignment information about each of the shot areas, which isonce determined on the measurement/exchange station, is determined(stored) on the basis of the fiducial mark PFM of the fiducial plate.When the liquid immersion exposure is executed on the exposure station,the movement of the first substrate stage PST1 is controlled so thateach of the shot areas is positioned on the basis of the positionalrelationship between the mask M and the fiducial mark MFM formed in thepredetermined positional relationship with respect to the fiducial markPFM of the fiducial plate. That is, the alignment information about eachof the shot areas determined on the measurement/exchange station iseffectively delivered to the exposure station by using the fiducialmarks PFM, MFM.

As described above, in the case of the twin-stage type exposureapparatus, the measurement process can be performed not through theliquid on the other stage during the liquid immersion exposure processperformed on one stage. Therefore, it is possible to improve thethroughput of the exposure process. The structure and the exposureoperation of the twin-stage type exposure apparatus are disclosed, forexample, in Japanese Patent Application Laid-open Nos. 10-163099 and10-214783 (corresponding to U.S. Pat. Nos. 6,341,007, 6,400,441,6,549,269, and 6,590,634), Published Japanese Translation of PCTInternational Publication for Patent Application No. 2000-505958(corresponding to U.S. Pat. No. 5,969,441), and U.S. Pat. No. 6,208,407,the disclosures of which are incorporated herein by reference within arange of permission of the domestic laws and ordinances of the statedesignated or selected in this international application.

The focus/leveling-detecting system 14 is arranged on the exposurestation of the twin-stage type exposure apparatus described above.However, as disclosed in U.S. Pat. No. 6,208,407, thefocus/leveling-detecting system of the exposure station may be omitted,and the positional relationship between the image plane of theprojection optical system PL and the surface of the substrate P may beadjusted by using an interferometer for measuring the positioninformation of the substrate stage PST in the Z direction. Of course,the interferometer for measuring the position information of thesubstrate stage PST in the Z direction and the focus/leveling-detectingsystem 14 may be used in combination.

In the embodiment described above, the fiducial mark MFM of the fiducialplate (for example, the fiducial plate 42) is detected by the maskalignment system 19 through the liquid 50. However, a transparent member(cover glass, correcting member) having a predetermined thickness may bearranged on the fiducial mark MFM, and the fiducial mark MFM may bedetected by the mask alignment system 19 not through the liquid. In thisprocedure, a pseudo-liquid immersion state is formed between theprojection optical system PL and the fiducial mark MFM by thetransparent member. Therefore, it is possible to correctly measure theprojection position information about the image of the pattern of themask M by using the fiducial mark MFM even not through the liquid.Therefore, not only the alignment mark on the substrate P but also thefiducial mark MFM is detected not through the liquid. Therefore, it ispossible to stably and correctly determine the alignment information inorder to effect the positional alignment between the mask M and thesubstrate P.

The arrangement of the mask alignment system 19 is not limited to anarrangement as disclosed in Japanese Patent Application Laid-open No.7-176468 (corresponding to U.S. Pat. No. 5,646,413). It is enough todetect the positional relationship between the mask M (mark of the maskM) and the fiducial or the reference (MFM) on the substrate stage PST.

In the embodiment described above, the liquid is supplied onto thesubstrate P after detecting the alignment mark on the substrate Pwithout using the liquid. Therefore, for example, the deformation(expansion or shrinkage) of the substrate P and the deformation of thesubstrate stage PST are caused by the weight of the liquid and thetemperature of the liquid. Even if the liquid immersion exposure isperformed in this state on the basis of the position information aboutthe alignment mark and the surface information about the substrate Pdetected under the dry condition, then the error such as the positionaldeviation or the defocus arises, and there is such a possibility thatthe pattern image of the mask M is not projected onto the substrate P ina desired state.

In such a case, the following procedure may be available. That is, anycorrection information (map information) is previously prepared in orderto correct the deviation of the positional alignment caused by thesupply of the liquid onto the substrate P, by using, for example, atechnique as disclosed, for example, in Japanese Patent ApplicationLaid-open No. 2002-353121 (United States Patent Publication No.2002/0042664A) in relation to the positional alignment (alignment)between the pattern image and each of the shots on the substrate P. Thecorrection information is added to the position information about thealignment mark of the substrate P detected under the dry condition toperform the positional alignment between the pattern image and each ofthe shot areas on the substrate P. Alternatively, any test exposure maybe performed to determine similar correction information according tothe amount of positional deviation of the pattern of each of the shots,and the positional alignment may be performed between the substrate Pand each of the shot areas by using the correction information.

As for the focus/leveling control as well, the following procedure maybe available. That is, for example, any test exposure is performed topreviously determine the correction information in order to correct theerror (defocus or the like) caused by the supply of the liquid onto thesubstrate P. The correction information is added to the surfaceinformation about the substrate P detected under the dry condition toadjust the positional relationship between the surface of the substrateP and the image plane formed through the liquid by the projectionoptical system PL.

As described above, pure water is used as the liquid 50 in thisembodiment. Pure water is advantageous in that pure water is availablein a large amount with ease, for example, in the semiconductorproduction factory, and pure water exerts no harmful influence, forexample, on the optical element (lens) and the photoresist on thesubstrate P. Further, pure water exerts no harmful influence on theenvironment, and the content of impurity is extremely low. Therefore, itis also expected to obtain the function to wash the surface of thesubstrate P and the surface of the optical element provided at the tipsurface of the projection optical system PL.

It is approved that the refractive index n of pure water (water) withrespect to the exposure light beam EL having a wavelength of about 193nm is approximately in an extent of 1.44 to 1.47. When the ArF excimerlaser beam (wavelength: 193 nm) is used as the light source of theexposure light beam EL, then the wavelength is shortened on thesubstrate P by 1/n, i.e., to about 131 to 134 nm, and a high resolutionis obtained. Further, the depth of focus is magnified about n times,i.e., about 1.44 to 1.47 times as compared with the value obtained inthe air. Therefore, when it is enough to secure an approximatelyequivalent depth of focus as compared with the case of the use in theair, it is possible to further increase the numerical aperture of theprojection optical system PL. Also in this viewpoint, the resolution isimproved.

In the embodiment described above, the lens 60 is attached to the tip ofthe projection optical system PL. However, the optical element, which isattached to the tip of the projection optical system PL, may be anoptical plate which is usable to adjust the optical characteristics ofthe projection optical system PL, for example, the aberration (forexample, spherical aberration and comatic aberration). Alternatively,the optical element may be a parallel plane plate through which theexposure light beam EL is transmissive. When the optical element, whichmakes contact with the liquid 50, is the parallel plane plate which ischeaper than the lens, it is enough that the parallel plane plate ismerely exchanged immediately before supplying the liquid 50 even whenany substance (for example, any silicon-based organic matter), whichdeteriorates the transmittance of the projection optical system PL, theilluminance of the exposure light beam EL on the substrate P, and theuniformity of the illuminance distribution, is adhered to the parallelplane plate, for example, during the transport, the assembling, and/orthe adjustment of the exposure apparatus EX. An advantage is obtainedsuch that the exchange cost is lowered as compared with the case inwhich the optical element to make contact with the liquid 50 is thelens. That is, the surface of the optical element to make contact withthe liquid 50 is dirtied, for example, due to the adhesion of scatteredparticles generated from the resist by being irradiated with theexposure light beam EL or any impurity contained in the liquid 50.Therefore, it is necessary to periodically exchange the optical element.However, when the optical element is the cheap parallel plane plate,then the cost of the exchange part is low as compared with the lens, andit is possible to shorten the time required for the exchange. Thus, itis possible to suppress the increase in the maintenance cost (runningcost) and the decrease in the throughput.

When the pressure, which is generated by the flow of the liquid 50, islarge between the substrate P and the optical element disposed at thetip of the projection optical system PL, it is also allowable that theoptical element is tightly fixed so that the optical element is notmoved by the pressure, rather than allowing the optical element to beexchangeable.

The liquid 50 is water in the embodiment described above. However, theliquid 50 may be any liquid other than water. For example, when thelight source of the exposure light beam EL is the F₂ laser, the F₂ laserbeam is not transmitted through water. Therefore, in this case, theliquid 50 may be, for example, fluorine-based oil (liquid) orperfluoropolyether (PFPE) through which the F₂ laser beam istransmissive. Alternatively, other than the above, it is also possibleto use, as the liquid 50, those (for example, cedar oil) which have thetransmittance with respect to the exposure light beam EL, which have therefractive index as high as possible, and which are stable against thephotoresist applied to the surface of the substrate P and the projectionoptical system PL.

The substrate P, which is usable in the respective embodiments describedabove, is not limited to the semiconductor wafer for producing thesemiconductor device. Those applicable include, for example, the glasssubstrate for the display device, the ceramic wafer for the thin filmmagnetic head, and the master plate (synthetic quartz, silicon wafer)for the mask or the reticle usable for the exposure apparatus.

In the embodiment described above, the exposure apparatus is adopted, inwhich the space between the projection optical system PL and thesubstrate P is locally filled with-the liquid. However, the presentinvention is also applicable to a liquid immersion exposure apparatus inwhich a stage for holding a substrate as an exposure objective is movedin a liquid tank, and a liquid immersion exposure apparatus in which aliquid tank having a predetermined depth is formed on a stage and asubstrate is held therein. The structure and the exposure operation ofthe liquid immersion exposure apparatus in which the stage for holdingthe substrate as the exposure objective is moved in the liquid tank aredisclosed in detail, for example, in Japanese Patent ApplicationLaid-open No. 6-124873. The structure and the exposure operation of theliquid immersion exposure apparatus in which the liquid tank having thepredetermined depth is formed on the stage and the substrate is heldtherein are disclosed in detail, for example, in Japanese PatentApplication Laid-open No. 10-303114 and U.S. Pat. No. 5,825,043. Thedisclosures of these documents are incorporated herein by referencewithin a range of permission of the domestic laws and ordinances of thestate designated or selected in this international application.

As for the exposure apparatus EX, the present invention is alsoapplicable to the scanning type exposure apparatus (scanning stepper)based on the step-and-scan system for performing the scanning exposurefor the pattern of the mask M by synchronously moving the mask M and thesubstrate P as well as the projection exposure apparatus (stepper) basedon the step-and-repeat system for performing the full field exposure forthe pattern of the mask M in a state in which the mask M and thesubstrate P are stood still, while successively step-moving thesubstrate P. The present invention is also applicable to the exposureapparatus based on the step-and-stitch system in which at least twopatterns are partially overlaid and transferred on the substrate P.

As for the type of the exposure apparatus EX, the present invention isnot limited to the exposure apparatus for the semiconductor productionapparatus for exposing the substrate P with the semiconductor devicepattern. The present invention is also widely applicable, for example,to the exposure apparatus for producing the liquid crystal displaydevice or for producing the display as well as the exposure apparatusfor producing, for example, the thin film magnetic head, the imagepickup device (CCD), the reticle, or the mask.

When the linear motor is used for the substrate stage PST and/or themask stage MST, it is allowable to use any one of those of the airfloating type based on the use of the air bearing and those of themagnetic floating type based on the use of the Lorentz's force or thereactance force. Each of the stages PST, MST may be either of the typein which the movement is effected along the guide or of the guidelesstype in which no guide is provided. An example of the use of the linearmotor for the stage is disclosed in U.S. Pat. Nos. 5,623,853 and5,528,118, the disclosures of which are incorporated herein by referencewithin a range of permission of the domestic laws and ordinances of thestate designated or selected in this international application.

As for the driving mechanism for each of the stages PST, MST, it is alsoallowable to use a plane motor in which a magnet unit provided withtwo-dimensionally arranged magnets and an armature unit provided withtwo-dimensionally arranged coils are opposed to each other, and each ofthe stages PST, MST is driven by the electromagnetic force. In thisarrangement, any one of the magnet unit and the armature unit isconnected to the stage PST, MST, and the other of the magnet unit andthe armature unit is provided on the side of the movable surface of thestage PST, MST.

The reaction force, which is generated in accordance with the movementof the substrate stage PST, may be mechanically released to the floor(ground) by using a frame member so that the reaction force is nottransmitted to the projection optical system PL. The method for handlingthe reaction force is disclosed in detail, for example, in U.S. Pat. No.5,528,118 (Japanese Patent Application Laid-open No. 8-166475), thedisclosures of which are incorporated herein by reference within a rangeof permission of the domestic laws and ordinances of the statedesignated or selected in this international application.

The reaction force, which is generated in accordance with the movementof the mask stage MST, may be mechanically released to the floor(ground) by using a frame member so that the reaction force is nottransmitted to the projection optical system PL. The method for handlingthe reaction force is disclosed in detail, for example, in U.S. Pat. No.5,874,820 (Japanese Patent Application Laid-open No. 8-330224) Thecontents of the descriptions in the documents are incorporated herein byreference within a range of permission of the domestic laws andordinances of the state designated or selected in this internationalapplication.

As described above, the exposure apparatus EX according to theembodiment of the present invention is produced by assembling thevarious subsystems including the respective constitutive elements asdefined in claims so that the predetermined mechanical accuracy, theelectric accuracy, and the optical accuracy are maintained. In order tosecure the various accuracies, those performed before and after theassembling include the adjustment for achieving the optical accuracy forthe various optical systems, the adjustment for achieving the mechanicalaccuracy for the various mechanical systems, and the adjustment forachieving the electric accuracy for the various electric systems. Thesteps of assembling the various subsystems into the exposure apparatusinclude, for example, the mechanical connection, the wiring connectionof the electric circuits, and the piping connection of the air pressurecircuits in correlation with the various subsystems. It goes withoutsaying that the steps of assembling the respective individual subsystemsare performed before performing the steps of assembling the varioussubsystems into the exposure apparatus. When the steps of assembling thevarious subsystems into the exposure apparatus are completed, theoverall adjustment is performed to secure the various accuracies as theentire exposure apparatus. It is desirable that the exposure apparatusis produced in a clean room in which, for example, the temperature andthe cleanness are managed.

As shown in FIG. 7, the microdevice such as the semiconductor device isproduced by performing, for example, a step 201 of designing thefunction and the performance of the microdevice, a step 202 ofmanufacturing a mask (reticle) based on the designing step, a step 203of producing a substrate as a base material for the device, an exposureprocess step 204 of exposing the substrate with a pattern of the mask byusing the exposure apparatus EX of the embodiment described above, astep of assembling the device (including a dicing step, a bonding step,and a packaging step) 205, and an inspection step 206.

According to the liquid immersion exposure apparatus and the liquidimmersion exposure method of the present invention, the detection of thesurface information about the substrate surface and the detection of thealignment mark on the substrate are performed not through the liquid forthe liquid immersion exposure, and then the liquid immersion exposure isperformed on the basis of the obtained information. Therefore, it ispossible to correctly perform the adjustment of the positionalrelationship between the substrate surface and the image plane formedthrough the liquid and the positional alignment between each of the shotareas on the substrate and the projection position of the pattern image.Therefore, it is possible to perform the highly accurate exposureprocess, and it is possible to produce the device which exhibits thedesired performance.

1. An exposure apparatus comprising: a projection optical system forprojecting a pattern on a reticle onto an object to be exposed; areference mark that serves as a reference for an alignment between thereticle and the object; a first fluid that has a refractive index of 1or greater, and fills a space between at least part of said projectionoptical system and the object and a space between at least part of saidprojection optical system and the reference mark; and an alignmentmechanism for aligning the object by using said projection opticalsystem and the first fluid.
 2. An exposure apparatus according to claim1, further comprising: a stage for mounting the object; and a referenceplate mounted on said stage and made of a transparent material thattransmits light, wherein said reference mark is provided on thereference plate.
 3. An exposure apparatus according to claim 2, whereinsaid alignment mechanism includes a light-receiving element provided onsaid reference plate at a back of a surface on which said reference markis formed, the light-receiving reference mark, wherein said exposureapparatus further comprises a second fluid that has a refractive indexof 1 or greater, and fills a space between said reference mark and thelight-receiving element.
 4. An exposure apparatus according to claim 3,wherein said alignment mechanism further includes a plane-convex lensprovided between said reference mark and the light-receiving element,the plane-convex lens having a plane opposing to the back of saidreference plate, wherein the second fluid fills a space between saidreference mark and the plane-convex lens.
 5. An exposure apparatusaccording to claim 2, wherein said alignment mechanism includes alight-receiving element provided on said reference plate at a back of asurface on which said reference mark is formed, the light-receivingelement receiving light that transmits the reference mark, wherein theback of said reference plate has a convex shape having a curvature thatdoes not cause a total reflection of the light.
 6. An exposure apparatusaccording to claim 1, wherein said alignment mechanism has aplane-convex lens having a plane opposing to a back of a surface of saidreference plate, on which surface said reference mark is formed, theplane being spaced from the back by a distance so that light thattransmits the reference mark is not totally reflected on the back ofsaid reference plate.
 7. An exposure apparatus according to claim 5,wherein the distance is smaller than the wavelength of the light.
 8. Anexposure apparatus according to claim 1, wherein said alignmentmechanism includes a light-receiving element for receiving light thattransmits said reference mark, wherein said exposure apparatus furthercomprises a second fluid that fills a space between the reference markand the light-receiving element, and has a refractive index of 1 orgreater.
 9. An exposure apparatus according to claim 1, wherein saidalignment mechanism includes an irradiating section for irradiatinglight that transmits said reference mark and enters said projectionoptical system, wherein said exposure apparatus further comprises asecond fluid that fills a space between said reference mark and theirradiating section, and has a refractive index of 1 or greater.
 10. Anexposure apparatus according to claim 2, wherein said alignmentmechanism includes an irradiating section arranged at a back of asurface of said reference plate, on which surface said reference mark isformed, wherein said exposure apparatus further comprises a second fluidthat immerses a space between the reference mark and the irradiatingsection, and has a refractive index of 1 or greater.
 11. An exposureapparatus comprising: a projection optical system for projecting apattern on a reticle onto an object; a reference mark that serves as areference for an alignment between the reticle and the object; alight-receiving element for receiving light that transmits saidreference mark; and a fluid that has a refractive index of 1 or greater,and fills a space between said reference mark and said light-receivingelement.
 12. An exposure apparatus according to claim 11, furthercomprising: a stage for mounting the object; and a reference platemounted on said stage and made of a transparent material that transmitslight, wherein said reference mark is provided on the reference plate.13. An exposure apparatus according to claim 12, wherein said alignmentmechanism further includes a plane-convex lens provided between saidreference mark and the light-receiving element, the plane-convex lenshaving a plane opposing to the back of said reference plate, wherein thefluid fills a space between said reference mark and the plane-convexlens.
 14. An exposure apparatus according to claim 11, wherein saidprojection optical system has a numerical aperture of 0.8 or greater.15. An exposure apparatus comprising: a projection optical system forprojecting a pattern on a reticle onto an object; a reference mark thatserves as a reference for an alignment between the reticle and theobject; an irradiating section for irradiating light that transmits saidreference mark and enters said projection optical system; and a fluidthat has a refractive index of 1 or greater, and fills a space betweensaid reference mark and said irradiating section.
 16. An exposureapparatus according to claim 15, further comprising: a stage formounting the object; and a reference plate mounted on said stage andmade of a transparent material that transmits light, wherein saidreference mark is provided on the reference plate.
 17. An exposureapparatus according to claim 16, wherein said alignment mechanismfurther includes a plane-convex lens provided between said referencemark and the light-receiving element, the plane-convex lens having aplane opposing to the back of said reference plate, wherein the fluidfills a space between said reference mark and the plane-convex lens. 18.An exposure apparatus comprising: a projection optical system forprojecting a pattern on a reticle onto an object; a reference mark thatserves as a reference for an alignment between the reticle and theobject; and an anti-reflection member for preventing a total reflectionof light that has passed said reference mark and has not yet beenreceived by said light-receiving element.
 19. An exposure apparatusaccording to claim 18, further comprising: a stage for mounting theobject; and a reference plate mounted on said stage and made of atransparent material that transmits light, wherein said reference markis provided on the reference plate, wherein said antireflection memberhas a convex shape that has a curvature that does not cause a totalreflection of the light, and is formed on a back of a surface of saidreference plate, on which surface said reference mark is formed.
 20. Anexposure apparatus according to claim 18, further comprising: a stagefor mounting the object; and a reference plate mounted on said stage andmade of a transparent material that transmits light, wherein saidreference mark is provided on the reference plate, wherein saidantireflection member includes a plane-convex lens that has a plane thatopposes a back of a surface of the reference plate, on which surfacesaid reference mark is formed, and is spaced from the back by a distanceso that light that passes the reference mark is not totally reflected onthe back of the reference plate.
 21. An exposure apparatus according toclaim 18, wherein the light-receiving element is a light intensitysensor for detecting a light intensity change of the light.
 22. Anexposure apparatus according to claim 21, further comprising acalculating section for calculating a positional relationship betweenthe reticle and the object in an optical-axis direction of saidprojection optical system, based on the light intensity change detectedby the light intensity sensor.
 23. An exposure apparatus according toclaim 21, further comprising a calculating section for calculating anaberration of said projection optical system based on the lightintensity change detected by said light intensity sensor.
 24. Anexposure apparatus comprising: a projection optical system forprojecting a pattern on a reticle onto an object; a light-receivingelement for receiving light that transmits said reference mark; and anadjuster, arranged between said reference mark and the light-receivingelement, for adjusting a numerical aperture of the light.
 25. Anexposure apparatus according to claim 24, wherein said adjuster has afluid that has a refractive index of 1 or greater, and fills a spacebetween said reference mark and said light-receiving element.
 26. Anexposure apparatus according to claim 24, wherein said exposureapparatus is an immersion type exposure apparatus that immerses at leastpart of said projection optical system in a fluid that has a refractiveindex of 1 or greater.
 27. An exposure method for exposing a pattern ona reticle onto an object, said exposure method comprising the step of:aligning the reticle and the object with each other by using lighthaving a numerical aperture of 1 or greater.
 28. An exposure methodaccording to claim 27, wherein at least part of the projection opticalsystem is filled with the fluid having a refractive index of 1 orgreater.
 29. A device manufacturing method comprising the steps of:exposing an object using an exposure apparatus according to claim 1; anddeveloping the object that has been exposed.